Sex-Specific Mechanisms of Resistance Vessel Endothelial Dysfunction Induced by Cardiometabolic Risk Factors

The incidence of obesity is rising, particularly among women. Microvascular dysfunction is more common with female sex, obesity, and hyperlipidemia and predicts adverse cardiovascular outcomes, but the molecular mechanisms are unclear. Because obesity is associated with mineralocorticoid receptor (MR) activation, we tested the hypothesis that MR in endothelial cells contribute to sex differences in resistance vessel dysfunction in response to cardiometabolic risk factors.

Male and female endothelial cell-specific MR knockout mice and MR-intact littermates were randomized to high-fat-diet-induced obesity or obesity with hyperlipidemia induced by adeno-associated virus-based vector targeting transfer of the mutant stable form (DY mutation) of the human PCSK9 (proprotein convertase subtilisin/kexin type 9) gene and compared with control diet. Female but not male mice were sensitive to obesity-induced endothelial dysfunction, whereas endothelial function was impaired in obese hyperlipidemic males and females. In males, obesity or hyperlipidemia decreased the nitric oxide component of vasodilation without altering superoxide production or endothelial nitric oxide synthase expression or phosphorylation. Decreased nitric oxide content in obese males was overcome by enhanced endothelium-derived hyperpolarization-mediated relaxation along with increased SK3 expression. Conversely, in females, endothelium-derived hyperpolarization was significantly impaired by obesity with lower IK1 expression and by hyperlipidemia with lower IK1 and SK3 expression, loss of H₂O₂-mediated vasodilation, and increased superoxide production. Endothelial cell-MR deletion prevented endothelial dysfunction induced by risk factors only in females. Rather than restoring endothelium-derived hyperpolarization in females, endothelial cell-MR deletion enhanced nitric oxide and prevented hyperlipidemia-induced oxidative stress.

These data reveal distinct mechanisms driving resistance vessel dysfunction in males versus females and suggest that personalized treatments are needed to prevent the progression of vascular disease in the setting of obesity, depending on both the sex and the metabolic profile of each patient.